You don't say if your church provides a nursery for babies and young children; most churches do, and if yours doesn't, you might want to suggest this to your pastor.
In any case, it's wrong to assume that children don't get anything out of church. Admittedly, they may not follow the sermon or listen to much else that goes on in the service. However, they'll realize that going to church is important to their parents, and to everyone else who attends. And as time passes, they'll realize that it should be important to them, too. Many children do like to be part of the singing, and those hymns will begin to be part of their memory.
Instead of being upset by children attending services at your church, I hope you'll thank God for them, and pray regularly for them and their parents. Most people come to Christ while they're still young, and God may be planting seeds of faith in the hearts of your church's children right now. God has promised that His Word "will not return to me empty, but will accomplish what I desire" (Isaiah 55:11).
In addition, do all you can to support your church's programs for its youth. Young people face challenges and pressures many of us never knew, and they need a solid moral and spiritual foundation to their lives -- one that comes from faith in Christ. Remember Jesus' words: "Let the little children come to me, and do not hinder them, for the kingdom of God belongs to such as these" (Mark 10:14).